Sail boats which harness wind to provide motive power have been used for centuries. Vehicles having runners secured to their bottom surfaces and having sails have utilized wind to cause the vehicles skate over surfaces of solid ice. However, while wheeled bicycles have been powered by human operators or by detachable motors, no one prior to applicant has succeeded to devising apparatus including a sail attachment connectable to a bicycle for harnessing wind to drive a bicycle forward in a controlled manner.